1. Field of the Invention
The invention relates to a manufacturing method for a high-pressure tank, and a high-pressure tank.
2. Description of Related Art
In recent years, there has been developed a vehicle that is driven by energy on combustion of fuel gas or electrical energy generated by electrochemical reaction of fuel gas. Such a vehicle may be equipped with a high-pressure tank that stores fuel gas, such as natural gas and hydrogen. In this case, in order to reduce the size of the high-pressure tank in consideration of mountability of the high-pressure tank on a vehicle while extending the cruising range of the vehicle, it is required to fill the high-pressure tank with fuel gas at a higher fill pressure.
In order to fill the high-pressure tank with fuel gas at a higher fill pressure, it is necessary to improve the strength of the high-pressure tank. Then, there is known a technique for forming a fiber reinforced plastics (FRP) layer on the outer surface of a metal or resin liner (inner casing) using filament winding as a technique for improving the strength of the high-pressure tank. Then, when the liner has a cylindrical portion that has a cylindrical shape and dome portions that have a domical shape and that are provided on both ends of the cylindrical portion, a fiber reinforced plastics layer formed by the filament winding generally mostly includes a hoop layer that is formed by hoop winding and a helical layer that is formed by helical winding. The hoop layer is mainly used to improve the strength against internal pressure applied in the circumferential direction of the liner (hereinafter, also referred to as “the circumferential strength of the liner”). On the other hand, the helical layer is mainly used to improve the strength against internal pressure applied in the axial direction of the liner (hereinafter, also referred to as “the axial strength of the liner”).
Incidentally, in an existing art, various techniques for improving the strength of a high-pressure tank that includes a fiber reinforced plastics layer on the outer surface of the liner have been suggested. For example, the strength of the high-pressure tank may be improved in such a manner that the fiber reinforced plastics layer is formed of alternately laminated hoop layers and helical layers (for example, see Japanese Patent Application Publication No. 2008-45660 (JP-A-2008-45660), Japanese Patent Application Publication No. 2004-293571 (JP-A-2004-293571) and Japanese Patent Application Publication No. 8-216277 (JP-A-8-216277).
However, there is room for improvement in the techniques described in JP-A-2008-45660, JP-A-2004-293571 and JP-A-8-216277 in terms of the reliability, that is, the pressure resistance and durability, of a high-pressure tank.